Configuring component carriers in carrier aggregation

ABSTRACT

A system and method for configuring component carriers in carrier aggregation is disclosed. The method comprises communicating a carrier aggregation capability for a selected UE to an enhanced Node B (eNode B) configured to provide service for a plurality of UEs. A plurality of component carriers at the eNode B can be configured for the selected UE based on the carrier aggregation capability of the selected UE. A component carrier configuration message is broadcast from the eNode B containing component carrier configuration information that is common to the plurality of UEs. Specific configuration information that is specific to the selected UE is communicated using dedicated communication signaling. Selected configured component carriers are then activated by the eNode B for the selected UE. Activation can be based on the UE&#39;s quality of service needs, bandwidth needs, and strength of signal for the component carriers.

CLAIM OF PRIORITY

Priority of U.S. Provisional patent application Ser. No. 61/330,837filed on May 3, 2010 is claimed and which is hereby incorporated byreference.

BACKGROUND

The use of wireless communication devices continues to become moreubiquitous in modern societies. The substantial increase in the use ofwireless devices is driven, in part, by the devices' increasingabilities. While wireless devices were once used only to communicatevoice and text, their ability to display audiovisual presentations hasdriven the need to be able to transmit and receive pictures, informationrelated to games, television, movies, and so forth.

One way of increasing the amount of data that can be communicated isthrough the use of carrier aggregation. Carriers are signals inpermitted frequency domains onto which information is placed. The amountof information that can be placed on a carrier is determined by thecarrier's bandwidth. The permitted frequency domains are often limitedin bandwidth. The bandwidth limitations become more severe when a largenumber of users are simultaneously using the bandwidth in the permittedfrequency domains.

Carrier aggregation enables multiple carrier signals to besimultaneously communicated between a user's wireless device and a basestation. Multiple different carriers can be used. In some instances, thecarriers may be from different permitted frequency domains. Thisprovides a broader choice to the wireless devices, enabling morebandwidth to be obtained. The greater bandwidth can be used tocommunicate bandwidth intensive operations, such as streaming video orlarge data files.

Various wireless standards have been drafted that enable wirelesscommunication devices to be interoperable. However, the wirelessstandards are not complete in defining the information that needs to beexchanged between wireless devices and base stations to allow carrieraggregation to take place in a mobile wireless communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the invention will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the invention; and, wherein:

FIG. 1 a illustrates carrier aggregation of continuous componentcarriers in accordance with an example;

FIG. 1 b illustrates carrier aggregation of non-continuous componentcarriers in accordance with an example;

FIG. 2 illustrates a block diagram of carrier aggregation in accordancewith an example;

FIG. 3 illustrates a block diagram of component carrier (CC) bandwidthsin accordance with an example;

FIG. 4 a illustrates pairing of uplinks and downlinks of componentcarriers for component carrier configuration in accordance with anexample;

FIG. 4 b illustrates asymmetric pairing with cross carrier allocation inaccordance with an example;

FIG. 4 c illustrates asymmetric pairing without cross carrier allocationin accordance with an example;

FIG. 5 illustrates a flow chart for carrier aggregation in accordancewith an example;

FIG. 6 illustrates a sequence of configuration, activation, andscheduling cycles for a component carrier involved in carrieraggregation in accordance with an example;

FIG. 7 depicts a flow chart of a method for configuring componentcarriers in carrier aggregation in accordance with an example; and

FIG. 8 depicts a flow chart of a system for configuring componentcarriers in carrier aggregation in accordance with an example.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to beunderstood that this invention is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting.

DEFINITIONS

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result.

EXAMPLE EMBODIMENTS

An initial overview of technology embodiments is provided below and thenspecific technology embodiments are described in further detail later.This initial summary is intended to aid readers in understanding thetechnology more quickly but is not intended to identify key features oressential features of the technology nor is it intended to limit thescope of the claimed subject matter. The following definitions areprovided for clarity of the overview and embodiments described below.

FIG. 1 a illustrates an example of carrier aggregation of continuouscarriers. In the example, three carriers are contiguously located alonga frequency band. Each carrier can be referred to as a componentcarrier. In a continuous type of system, the component carriers arelocated adjacent one another and are typically located within a singlefrequency band. A frequency band is a selected frequency range in theelectromagnetic spectrum. Selected frequency bands are designated foruse with wireless communications such as wireless telephony. Certainfrequency bands are owned or leased by a wireless service provider. Eachadjacent component carrier may have the same bandwidth, or differentbandwidths. A bandwidth is a selected portion of the frequency band.Wireless telephony has traditionally been conducted within a singlefrequency band.

FIG. 1 b illustrates an example of carrier aggregation of non-continuouscomponent carriers. The non-continuous component carriers may beseparated along the frequency range. Each component carrier may even belocated in different frequency bands. The ability to use componentcarriers in different frequency bands enables greater communicationspeeds and more efficient use of available bandwidth.

In existing spectrum allocation policies and the relatively narrowfrequency bands that are currently available for wireless telephony, itcan be difficult to allocate continuous large bandwidths, such asbandwidths of 100 MHz. The use of carrier aggregation enables multipledifferent carriers to be combined to enable greater bandwidths to beused to increase wireless communication speeds.

Wireless mobile communication technology uses various standards andprotocols to transmit data between a base transceiver station (BTS) anda wireless mobile device. In the third generation partnership project(3GPP) long term evolution (LTE) standard, the BTS is a combination ofevolved Node Bs (eNode Bs or eNBs) and Radio Network Controllers (RNCs)in a Universal Terrestrial Radio Access Network (UTRAN), whichcommunicates with the wireless mobile device, known as a user equipment(UE). Data is transmitted from the eNode B to the UE via a physicaldownlink shared channel (PDSCH). As a UE changes positions (i.e. moves),the UE can be moved from one eNode B to another. The process of movingbetween nodes is typically referred to as handover. The handover processtypically occurs in a seamless fashion so that a user does not evenrealize it occurs. The eNode B that provides communication services,such as the PDSCH, to a UE is referred to as the serving eNode B.

While the terminology of the 3GPP LTE standard is used throughout thisspecification, it is not intended to be limiting. A UE configured tocommunicate with an eNode B is considered to be synonymous with ageneric radio frequency mobile communication device configured tocommunicate with a base station, unless otherwise noted.

In one embodiment of carrier aggregation (CA) in the 3GPP LTE standard,component carriers (CCs) for a Universal Mobile TelecommunicationsSystem (UMTS) Terrestrial Radio Access Network can be combined togetherto form a larger bandwidth for the UE, as illustrated in FIG. 2. Forexample, the UMTS may have a system bandwidth 210 of 100 MHz in afrequency spectrum 216 with each CC 212 having a 20 MHz bandwidth. EachCC may comprise a plurality of subcarriers 214. Some UEs 230 may use theentire 100 MHz system bandwidth by aggregating five 20 MHz CCs togetherto achieve a 100 MHz UE bandwidth 220.

In another example, two UEs 232 a and 232 b, each with a 40 MHzbandwidth capability, may each use two 20 MHz CCs together to achieve a40 MHz UE bandwidth 222 for each UE. In another example, each UE 234 a,234 b, 234 c, 234 d, and 234 e may use a single 20 MHz CC to achieve a20 MHz UE bandwidth 224. The CCs at an eNode B may be aggregated forsome UEs while other UEs may use a single CC during the same interval.For example, one UE with a 40 MHz bandwidth may be configured whilethree UEs that each use a single 20 MHz CC are employed in a 100 MHzbandwidth system (not shown). Carrier aggregation allows the bandwidthfor a UE to be adjusted and adapted by an eNode B based on the wirelesscommunication system's limitations, the UEs capabilities and bandwidthrequirements, the bandwidth available to the system and/or loading ofother UEs on the system.

Each UMTS may use a different carrier bandwidth, as illustrated in FIG.3. For example, the 3GPP LTE Release 8 (Rel-8) carrier bandwidths andRelease 10 (Rel-10) CC bandwidths can include: 1.4 MHz 310, 3 MHz 312, 5MHz 314, 10 MHz 316, 15 MHz 318, and 20 MHz 320. The 1.4 MHz CC caninclude 6 Resource Blocks (RBs) comprising 72 subcarriers. Each RB caninclude twelve 15 kHz subcarriers (on the frequency axis) and 6 or 7orthogonal frequency-division multiplexing (OFDM) symbols persubcarrier. The 3 MHz CC can include 15 RBs comprising 180 subcarriers.The 5 MHz CC can include 25 RBs comprising 300 subcarriers. The 10 MHzCC can include 50 RBs comprising 600 subcarriers. The 15 MHz CC caninclude 75 RBs comprising 900 subcarriers. The 20 MHz CC can include 100RBs comprising 1200 subcarriers. These examples are not intended to belimiting. Carrier aggregation can be accomplished using additionalschemes with different bandwidths and different numbers of subcarriersin each CC.

Each eNode B can have a plurality of different carriers. For instance,the eNode B may have five separate carriers. Each carrier can have aspecific bandwidth and center frequency. The carriers may be located inthe same frequency band or different frequency bands.

In one embodiment, an eNode B can be configured to broadcast or unicastinformation regarding its available carriers. For instance, informationmay be communicated using Radio Resource Control (RRC) signalingregardless of the carrier aggregation support of each UE being served bythe eNode B. RRC signaling is defined in Release 8 and further definedin Release 9 of the 3GPP LTE Standard, though use of the term isintended to be inclusive of future standards releases as well.

Each available carrier for an eNode B may be assigned an eNode Bspecific carrier index (eNB CI) by the eNode B. That is, the CI isspecific to the eNode B. If a UE is handed over to another eNode B, anew eNB CI will be assigned that eNode B. The eNB CI can be used forfuture referencing by the eNode B.

If the information about available carriers is static and the sameacross a network then the information can be provided to the UEfollowing network entry and during provisioning of the UE. Duringnetwork entry, the UE can provide the eNode B with its carrieraggregation capabilities. The UE's carrier aggregation capabilitiesinclude a maximum number of carriers that can be accepted. The maximumnumber of carriers can be defined for both the uplink (UL) and thedownlink (DL). In one embodiment, the UE may be configured to accept thesame number of uplink and downlink component carriers. Alternatively, agreater number of UL or DL CCs may be applied. For instance, the UE maybe configured to use 3 UL CCs and 5 DL CCs.

The capabilities of the UE can also include the bandwidth of eachcarrier that the UE is capable of accepting. As previously discussed,carriers with a number of different bandwidths may be used by the eNodeB. The UE can also communicate to the eNode B which different frequencyband classes are supported. For example, Global System for MobileCommunications (GSM) compatible phones may operate at frequency bandswith center frequencies at 380, 410, 450, 480, 710, 750, 810, 850, 900,1800 and 1900 MHz. Universal Mobile Telecommunications System (UMTS)compatible phones may operate at 700, 800, 850, 900, 1500, 1700, 1800,1900, 2100, and 2600 MHz when using frequency division duplexing (FDD).Other types of mobile phones can operate at additional frequencies andfrequency bands, as can be appreciated. Each country typically specifieswhich bands may be used within the country for mobile telephony.

The information about each UE's capabilities can be maintained andprovided to the serving eNode B during network entry or as part of RRClevel carrier configuration messaging when such configuration isinitiated by the eNode B.

Primary Component Carrier

When a UE that is configured to operate in a manner that is consistentwith the 3GPP LTE Rel 8/9 procedures is powered on then the UE istypically configured to scan, select, and attach to one of the availablecarriers provided by an eNode B. It can be assumed that all RRC-IDLEmode procedures are handled by each UE consistent with the 3GPP LTE Rel8/9 procedures as well.

The carrier selected by the UE for attachment to the eNode B can beconsidered the initial and default carrier, referred to herein as thePrimary Component Carrier (PCC). All other carriers used by the eNode Bcan be referred to as Secondary Component Carriers (SCC). A UE's PCC maybe changed for a variety of purposes. For instance, the PCC may bechanged due to load balancing, interference management, or other linklevel preferences. The change can be effected through the use of RRClevel carrier configuration updates without using network levelsignaling.

The PCC can carry system information such as paging and RRC messagingfor each UE's state and mobility management. The information may bebroadcast or unicast. In one embodiment, the system information can beexchanged between the eNode B and each UE consistent with 3GPP LTE Rel8/9 procedures. The RRC messages to each UE can be sent to the UEthrough other active carriers if the messages are part of the physicaldownlink control channel (PDCCH) information. A physical downlinkcontrol channel (PDCCH) is used to transfer downlink control information(DCI) that informs the UE about resource allocations or schedulingrelated to downlink resource assignments on the PDSCH, uplink resourcegrants, and uplink power control commands. The PDCCH can be transmittedprior to the PDSCH in each subframe transmitted from the eNode B to theUE.

The PCC can be configured and activated by default. The carrier that isselected by the UE for attachment to the eNode B at power up can bedesignated as the PCC. The PCC can remain activated while the UE is inan RRC-Connected mode. The PCC can be changed dynamically for purposessuch as load balancing, interference, link optimization, and so forth. Achange in the PCC can be initiated by the eNode B or requested by theUE. The change in PCC is not specifically discussed in the 3GPP LTE Rel8/9 versions of the standard.

In one embodiment, a security key update for a PCC change can beimplemented. For instance, the PCC change can follow a handoverprocedure such as the procedure laid out in the 3GPP Rel 8/9. The PCCchange can be carried out in a manner that enables the change to besubstantially transparent to upper layers of the network.

The PCC can be comprised of a downlink portion and an uplink portion.The DL PCC can be paired with an UL CC that carries the random accesschannel (RACH) and the physical uplink control channel (PUCCH)associated with the CCs for each active downlink. Alternatively, othercarriers of the eNode B can be configured to carry additional RACH's orPUCCH's based on the services needed by the UE and based on the UE'scapabilities.

Carrier Configuration/Reconfiguration

In one embodiment, an eNode B that is configured to support carrieraggregation can provide an attached UE with scheduling information(SI)about alternative (secondary) component carriers in that eNode Busing a high level signaling mechanism such as RRC signaling or anothertype of layer two or layer three signaling. The eNode B can communicateconfiguration information about each component carrier to the UEs thatare being served by the eNode B. When the UE receives this information,each alternative component carrier can be treated as a configuredcomponent carrier. This enables the UE to quickly activate configuredcomponent carriers. The configured component carrier's resources can bescheduled for carrier aggregation as needed. The carrier configurationinformation can be valid within an eNode B. Component Carriers aretypically configured as DL and UL component carrier pairs. Eachcomponent carrier pair, and its corresponding resources, can be referredto as a serving cell for the UE. Thus, component carrier configurationmay also be considered as cell configuration.

In one embodiment, carrier configuration information can be extended tobe changed for another eNode B during handover procedures. A next eNodeB can be referred to as a target eNode B. The component carrierconfiguration information can be communicated to the target eNode B aspart of component carrier pre-configuration, which may be integratedwith handover signaling.

The component carrier configuration information can include radio layerinformation for the uplink and downlink for each component carrier(cell). For example, the information can include details regarding theUL and DL component carriers' center frequency, bandwidth, duplex mode,and eNode B specific carrier index. The duplex mode may be time divisionduplex (TDD) or frequency division duplex (FDD). In addition, the duplexmode may be different for a component carrier's UL and DL. For instance,the UL may have a TDD duplex mode, while the downlink may have an FDDduplex mode, and vice versa.

The component carrier configuration information may be broadcast or sentthrough dedicated RRC signaling by the eNode B. To reduce the signalingoverhead used for subsequent reconfiguration and activation ordeactivation, each configured carrier can also be assigned a UE specificconfigured physical carrier index (CI). The UE specific CI can be usedfor subsequent references to that carrier in future layer 2 or layer 3messaging, such as RRC signaling.

In one embodiment, the eNode B can be configured to broadcast componentcarrier information that is common to a plurality of the UEs served bythe eNode B. Alternatively, broadcasting of component carrierconfiguration information may only be done when the information appliesto all of the UEs served by the eNode B. Component carrier informationthat is UE specific can be communicated using dedicated radio resourcecommunication signaling, such as RRC signaling or another type ofunicast signaling. For instance, information such as a componentcarrier's center frequency, the carrier's bandwidth, and the carrier'seNode B specific CI is the same for all UEs served by the eNode B. Thisinformation can be broadcast by the eNode B. The ability to broadcastthis information can significantly reduce signaling overhead. UEspecific information, such as the duplex mode for a specific UL or DL,and a UE specific configured physical carrier index for a componentcarrier can be communicated to the desired UE using RRC signaling oranother form of layer 2 or layer 3 signaling.

Once carriers are configured, they can be selected by the eNode B for aUE based on the UE's capabilities. For instance, the eNode B can takeinto account the number of component carriers for both uplink anddownlink that the UE can support, the maximum bandwidth the UE cansupport, the frequency bands the UE is capable of operating in, and soforth.

The carrier configuration may be deferred until wireless service betweena specific UE and the eNode B requires or benefits from carrieraggregation. This determination can be made by the eNode B based on theUE's communication needs. The UE's communication needs can be based oninformation such as the desired Quality of Service (QoS), bandwidthneeds, and so forth.

One or more component carriers that are configured for a specific UE canhave its configuration changed in a process referred to as carrierreconfiguration. Carrier reconfiguration is an RRC procedure to changeone or more of the configured carriers and/or a parameter of aconfigured carrier in the specific UE's set of configured componentcarriers.

Once the carriers have been configured for a specific UE, and before theconfigured carriers have been assigned to the UE by the eNode B, thespecific UE can perform signal strength measurements for each configuredcomponent carrier between the UE and the eNode B. In one embodiment, themeasurements can be similar to mobility based measurements. Thethreshold for triggering such measurements may be specifically definedfor a configured component carrier set management by the eNode B.

In one embodiment, the measurements may be radio resource management(RRM) type measurements. The RRM measurements may be a reference symbolreceived power (RSRP) measurement, a reference symbol received quality(RSSQ) measurement, a carrier received signal strength indicator (RSSI)measurement, or another type of measurement operable to provide anaveraged measurement of the link quality. In one embodiment, the RRMmeasurements may be averaged for approximately 200 milliseconds toreduce the effects of rapid changes in the component carrier signals.The set of configured carriers for the specific UE can be determined anddynamically managed through RRC signaling based on the UE's capabilitiesand signal strength measurement reports from the specific UE to theeNode B for each configured component carrier.

Carrier Pairing/Linking and Control Channel Mapping

Component carrier configuration also includes information about DL/ULparing as well as DL/UL control channel mapping and relevance across thecomponent carriers.

Each configured component carrier can include a DL CC paired with acorresponding UL CC. In one embodiment, the default pairing between eachDL CC and the corresponding UL CC can be based on the 3GPP LTE Release8/9 standards and reflected in System Information Block (SIB) messaging.However, such pairing may be changed as part of the CC configuration fora specific UE. For example, DL/UL paring options can support many-to-oneDL to UL configurations and many-to-one UL to DL configurations. Foreach configured carrier pair, the carrier for which the PDCCH istransmitted can also be defined.

There can be two PDCCH mapping/monitoring options. In one embodiment,for each active DL CC, the carrier on which the corresponding PDCCH istransmitted is explicitly defined during the RRC CA configurationprocess. The definition can apply in all subsequent scheduling,activation and deactivation. Such cross carrier PDCCH mappingconfiguration may be changed if needed through a CC reconfigurationprocedure.

In another embodiment, for each active DL or UL CC, the PDCCH carryingthe DL/UL scheduling information is either transmitted on the same CC orthe PCC, as specified in the RRC CA configuration process.

In either embodiment, the UE can know, following configuration, on whichactivated carrier it should monitor the PDCCH. This enables the UE toreduce the number of carriers on which blind detection of the PDCCH isrequired, thereby reducing the time and processing power needed todetermine the DCI at the UE.

Similarly, two different options are available for feedback channelmapping. In one embodiment, for each PDSCH transmission the PUCCHcarrying feedback information can be transmitted on the UL CC that ispaired with the DL CC carrying the corresponding PDCCH.

In another embodiment, the PUCCH for all PDSCH transmissions on all DLactive CCs is transmitted on the UL CC associated with the PCC. Thisembodiment can be preferred for cases in which the UE may not havemultiple UL CCs and/or when transmission on multiple UL CCs would impactlink level performance.

FIGS. 4 a-4 c illustrate various examples of CC DL/UL pairings. In theseexamples, the carriers are assigned numbers to distinguish between thecarriers. The numbering illustrated is for demonstration purposes onlyand is not intended to infer other types of numbering that may occur,such as the assigning of a carrier index value to each carrier of aneNode B.

In FIG. 4 a, the ability to pair UL and DL flexibly is illustrated. Forinstance, the UL CC for carrier 1 is linked with the DL CC for carrier 1to form a cell. Similarly, the UL CC for carrier 2 is linked with the DLCC for carrier 2 to form a cell. In another embodiment, the DL CC forcarrier 3 is linked with the UL CC for carrier 2. Thus, this cellcomprises an UL and a DL from two different carriers. The carriers maybe adjacent, or may have center frequencies at different parts of theradio spectrum. The UL and DL may even be located in different frequencybands. The carriers may also be duplexed using different schemes, suchas FDD or TDD.

FIG. 4 b illustrates an example of asymmetric pairing with cross carrierallocation. The physical downlink control channel (PDCCH) and physicaluplink control channel (PUCCH) for both carrier 1 and carrier 2 areallocated on carrier 1, while each DL CC supports its own physicaldownlink shared channel (PDSCH).

FIG. 4 c illustrates an example of asymmetric pairing without crosscarrier allocation. In the example of FIG. 4 c, the PDCCH1 and thePUCCH1 are allocated on carrier 1. The PUCCH2 is allocated on the UL CCfor carrier 1, while the PDCCH2 is allocated on the DL CC for carrier 2.As in FIG. 4 b, each DL CC supports its own PDSCH. A variety of othertypes of asymmetric pairing are possible, either with or without crosscarrier allocation, as can be appreciated.

A physical hybrid ARQ (Automatic Repeat request) indicator channel(PHICH) is a transmission channel that can carry information thatconfirms or requests the retransmission of blocks of data that werereceived incorrectly at the receiving device. For UL transmissions, thePHICH can be carried by the same carrier which contains the PDCCH forthe corresponding UL grant.

UE specific pairing can be defined if it is different than the defaultpairing based on the 3GPP LTE Release 8/9 standards and reflected in theSystem Information Block (SIB) messaging. For each DL CC, theconfiguration defines the corresponding UL carrier.

In one embodiment, the configuration information for each CC can show:

-   -   for each DL CC where the corresponding PUCCH is transmitted;    -   for each DL CC, where the corresponding PDCCH is transmitted;    -   for each UL CC where the corresponding PDCCH is transmitted; and    -   for each UL CC for which the DL is the default DL CC, as defined        in the 3GPP LTE Release 8/9 standards, whether the carrier        includes any random access channel (RACH); the default can be        that all RACH transmissions are carried on the PCC.

The PHICH can be sent on the same carrier where the PDCCH is transmittedfor both the DL CC and the UL CC in the example in the preceedingparagraph.

For each secondary component carrier (SCC), a DL configured carrier fora given UE can be linked to one UL configured carrier. The linking canapply for all UL control/feedback channel mechanisms including powercontrol, PUCCH, RACH (if configured) and non-CIF scheduling.

Component Carrier Activation

Once a component carrier has been configured, activation of theconfigured carrier can be performed at the layer 2 (L2) layer. Forexample, activation may be performed using the media access control(MAC) layer through MAC control elements. Activation is a procedure thatis typically used more frequently than configuration and less frequentlythan scheduling. There is little room for carrier aggregation specificinformation to be carried by MAC control elements during configuration,and even less room during scheduling. Therefore, only parameters whichare least likely to be changed upon activation or scheduling aretypically passed to the UE through configuration.

In one embodiment, deactivation of a carrier can be explicit andcombined with activation of another carrier. An activated carrier mayalso be deactivated implicitly after no data is scheduled on thatcarrier for a predefined period of time. The predefined period of timecan be set during the configuration/activation phase.

The activation information can include a list of configured CCs to beactivated and a list of activated CCs to be deactivated. In oneembodiment, the list can be implemented using a bitmap. The bitmap cancomprise an ordered list in which each CC is assigned a location on thelist. The location at which a CC is assigned on the list can be selectedas desired. For instance, a CC may be assigned a location on the listbased on the order in which the CC is activated, the CC's centerfrequency, the CC's carrier index (CI) value, or another process toassign a CC a unique location on the list. The activation ordeactivation of a CC can then be carried out in a binary fashion bysending one binary number to represent “Activate” and another binarynumber to represent “deactivate”.

For example, in carrier configuration each carrier can be assigned acarrier index value. An eNode B may have 5 configured carriers, withcarrier index values 1, 2, 4, 8 and 9. The carriers can be assigned to abitmap based on their carrier index value, with the lowest value listedfirst. A UE may be assigned carriers 1, 2, 4 and 9. The bitmap can bethe same length as the number of carriers used by a UE. Thus, the bitmapfor the UE is comprised of four binary numbers, with the value of eachnumber selected to represent the state of the carrier. A bitmap of“1111” may represent activation of each carrier. A bitmap of “0000” mayrepresent an explicit deactivation of each carrier. A bitmap value of“0101” may be used to activate carriers 1 and 4, while deactivatingcarriers 2 and 9 for the UE. Thus, the bitmap can be used tosimultaneously turn on selected configured carriers while turning othercarriers off. While the binary value “1” is represented to activate acarrier and the value “0” is represented to deactivate a carrier, thisis not considered to be limitation. The opposite binary values may beused to represent activation and deactivation, as can be appreciated.

The use of a bitmap can significantly reduce overhead. Multiple bits arenot needed to identify the carrier value and the desired state of thecarrier. The UE and the eNode B merely need to both understand whichposition each carrier is assigned to in the bitmap. A single bit canthen be transmitted to activate or deactivate a component carrier. Inone embodiment, the single bit can be used to activate or deactivate acell, comprising a UL CC and a DL CC. The UL CC and DL CC may be indifferent carriers.

In one embodiment, activation messages can be carried on the PCC and mayalso be sent on other carriers if they are configured to transmit PDCCH.A response to an activation message may be sent from the UE beforeactivation takes effect and allows one or more carriers to be scheduledto carry data. An activation confirmation from the UE to the eNode B canalso follow the same bitmap layout. The response can indicate which CCshave been successfully activated.

Once a CC has been activated at a UE, the UE can transmit a fastmeasurement of channel quality to the eNode B. For instance, a channelquality indicator (CQI) or other type of fast feedback channel can becommunicated to the eNode B to indicate receive channel qualityconditions on each carrier.

The activation process may be combined with the configuration process ifall of the configured carriers need to be activated. In this embodiment,configuration may be deferred until the eNode B obtains sufficientmeasurements from the UE on the strength of available carriers to ensurethat the candidate carrier is viable for activation before it isconfigured and activated.

FIG. 5 illustrates one example embodiment of a flow chart for carrieraggregation. The left line 502 represents communication to a UE 504. Thefirst line on the right represents a primary component carrier (PCC) 506at an eNode B 510. The second line on the right represents a secondarycomponent carrier (SCC) 508 at the eNode B 510. The eNode B can includea plurality of different SCCs, as previously discussed.

When the UE 504 enters a network served by the eNode B 510, acommunication 520 from the eNode B 510 can be sent to the UE identifyingthe available carriers in the network. The carrier selected by the UEfor attachment to the eNode B can be considered the initial and defaultcarrier, referred to as the Primary Component Carrier (PCC). All othercarriers used by the eNode B are referred to as Secondary ComponentCarriers (SCC).

The UE and eNode B can then communicate 522 for network entry andnegotiate the basic carrier aggregation capabilities of the UE. The UEcan learn the types of carriers offered by the eNode B, includingfrequency, bandwidth, and frequency band of the component carriers. TheUE can communicate its CA capabilities to the eNode B, including numberof UL and DL CCs it can accept, the bandwidths of each UL and DL the UEis capable of receiving, and the frequency bands the UE is capable ofoperating in.

The UE 504 can then communicate 524 to the eNode B 510 using RRCsignaling. The UE can communicate the UE's supported CA configurations.For instance, the candidate configured CCs.

The eNode B 510 can then communicate 526 to the UE specific carrierconfiguration information, including CIF allocation, DL/UL pairinginformation, PDCCH mapping information, PUCCH mapping, and so forth.

The UE 504 can then communicate 528 a scheduling request in the PCC. Thescheduling request can occur as if the UE were operating in a singlecarrier mode without possible carrier aggregation. The eNode B canrespond with a CC activation message 530. The CC activation message maybe sent via MAC headers or in the DCI on the PDCCH of the PCC 506. Aspreviously discussed, activation may include a bitmap showing whichheaders are to be activated and deactivated. An activation confirmationmay optionally be communicated 532.

Upon activation, the UE 504 can communicate 534 with the eNode B on boththe PCC 506 and at least one SCC 508. The UE can provide CQImeasurements for each active carrier to the eNode B. The CQImeasurements may be sent via the PCC 506.

The eNode B 510 can communicate 536 resource allocation information onone or more PDCCHs using the PCC 506. Cross carrier allocationinformation can also be communicated using CIF. In one embodiment, thePDCCH and cross carrier allocation information may also be sent from oneor more SCC 508. PDSCH and PUSCH data transmissions can be communicated538 from the eNode B on the PCC and SCC(s) to the UE 504. The UE cancommunicate 540 physical feedback channels on active carriers (PCC andSCC). This is typically done only for downlink multiple-carrierallocations only.

Finally, CC deactivation messages can be communicated 542 from the eNodeB 510 to the UE via the PCC 506. The deactivation messages may beexplicit or implicit. For instance, a deactivation message mayimplicitly be communicated if an activated CC has not used in a setamount of time, such as two minutes.

The flow chart of FIG. 5 is one example of a process in which CCs can beconfigured and activated for carrier aggregation on a UE. The example isnot intended to be limiting. The process may involve additional steps,and steps that occur in a different order than is listed in FIG. 5. Inaddition, each step listed in FIG. 5 may not be necessary each time a UEenters a network or is powered up.

FIG. 6 provides an example of a sequence of configuration, activation,and scheduling cycles for a CC involved in carrier aggregation. When aUE first enters a network the CCs at an eNode B are not configured 602.Through RRC communication between the UE and the eNode B, andbroadcasting from the eNode B, the CCs can be configured 604. Componentcarrier configuration information that is unique to a specific UE can becommunicated via RRC signaling. Component carrier configurationinformation that is not unique can be broadcast by the eNode B to all ofthe UEs served by the eNode B.

Once the CCs have been configured, the eNode B can activate a CC for aspecific UE based on the needs of the UE, such as Quality of Service(QoS), bandwidth, and so forth. If it is possible to meet the UE'scommunication needs using a single carrier, the eNode B may not assignadditional carriers to the UE. However, if additional carriers need tobe used to meet the communication needs of the UE then additionalcarriers can be assigned based on carrier measurements conducted by theUE for the eNode B's carriers. The carrier can then be activated 606 bythe eNode B using L2 communication such as MAC.

The activated CC can remain activated until explicitly instructed to bedeactivated 608 using L2 communication such as MAC. Alternatively the CCmay remain activated until implicit deactivation occurs due toinactivity on the CC for a specific period of time 610. A deactivated CCcan have its configuration removed 612, allowing the CC to bereconfigured using RRC signaling.

In another embodiment, a method 700 for configuring component carriersin carrier aggregation is disclosed, as depicted in the flowchart ofFIG. 7. The method comprises receiving 710 a carrier aggregationcapability from a selected user equipment (UE) at an enhanced Node B(eNode B) configured to provide service for a plurality of UEs withinthe eNode B's network. A plurality of component carriers are configured720 at the eNode B for the selected UE based on the carrier aggregationcapability of the selected UE.

The method 700 further comprises broadcasting 730 from the eNode Bcomponent carrier a configuration message containing component carrierconfiguration information that is common to the plurality of UEs andcommunicating 740 from the eNode B component carrier configurationinformation that is specific to one of the plurality of UEs usingdedicated communication signaling to form configured component carriers.The dedicated communication signaling can be RRC signaling from theeNode B to the selected UE for each component carrier.

The configuration information that is broadcast for each componentcarrier can include the component carrier's center frequency, bandwidth,and duplex mode, such as TDD or FDD. This configuration information maybe further defined for an uplink (UL) and downlink (DL) for each CC. Thebroadcast configuration message can also include an eNode B specificcarrier index. The dedicated communication signaling can include a UEspecific configured physical carrier index provided in the dedicatedcommunication signaling. Use of the eNode specific and UE specificcarrier index values can reduce overhead when referencing each componentcarrier in communication between the eNode B and the plurality of UEs.

The method further comprises activating 750 selected configuredcomponent carriers at the eNode B for the selected UE based on bandwidthand quality of service needs of the selected UE.

The method 700 can also include reporting radio resource management(RRM) measurements of signal strength from each of the plurality of UEsto the eNode B for a plurality of component carriers available forcarrier aggregation that are provided by the eNode B. The operation ofactivating selected configured component carriers at the eNode B for theselected UE can further comprise activating the selected configuredcomponents based on the RRM measurements provided by the selected UEfollowing configuration.

The operation of communicating the selected UE's carrier aggregationcapability can further comprise communicating from the selected UE atleast one of a maximum number of component carriers supported for anuplink to the eNode B, a maximum number of component carriers supportedfor a downlink from the eNode B, a maximum bandwidth supported for theuplink and the downlink, and support of selected frequency bands.

The method 700 can further comprise attaching the selected UE to one ofthe component carriers and defining the component carrier as a primarycomponent carrier. A downlink of the PCC and be selected to carrydownlink control information (DCI) on a physical downlink controlchannel (PDCCH) for the plurality of component carriers. In anotherembodiment, a downlink component carrier of the plurality of componentcarriers can be selected to carry DCI on the PDCCH for the plurality ofcomponent carriers.

The method 700 can further comprise selecting an uplink componentcarrier for each downlink component carrier to carry physical uplinkshared channel (PUSCH) and uplink feedback information on a physicaluplink control channel (PUCCH). The uplink component carrier can bepaired as part of carrier configuration with the downlink componentcarrier that is also carrying corresponding uplink assignments in thePDCCH. An uplink component carrier of the PCC can be selected to carryfeedback information for each physical downlink shared channel (PDSCH)transmission on each downlink component carrier for the plurality ofcomponent carriers. A physical hybrid ARQ (Automatic Repeat request)indicator channel (PHICH) can be carried on the same component carrierused to carry a PDCCH.

Activating the selected configured component carriers can furthercomprise transmitting activation information as a media access control(MAC) control element from the eNode B to the selected UE for eachcomponent carrier. Activating and deactivating each component carrierfor the selected UE can be accomplished using a bitmap transmitted fromthe eNode B to the UE. Bits in the bitmap can be mapped to an orderedlist of indexes for the plurality of component carriers. A “1” value canbe transmitted to activate a component carrier and a “0” value can betransmitted to deactivate a component carrier. Alternatively, theopposite binary values may also be used, as can be appreciated.Activated component carriers can also be deactivated based on selecteddeactivation rules. The deactivation rules can include the amount oftime a carrier has not been used to transmit data to a UE. After aselected amount of time, the component carrier may be deactivated if ithas not been used. Other rules can also be applied, as can beappreciated.

In another embodiment, a system 800 for configuring component carriersin carrier aggregation is disclosed, as depicted in the block diagram ofFIG. 8. The system comprises a carrier aggregation module 808 operatingat an enhanced Node B (eNode B) that is configured to provide servicefor a plurality of UEs. The eNode B is configured to receive a carrieraggregation capability from a carrier configuration module 802 operatingat a selected user equipment (UE).

The carrier aggregation module operating at the eNode B is operable toconfigure a plurality of component carriers at the eNode B for theselected UE based on the carrier aggregation capability of the selectedUE and broadcast from the eNode B a component carrier configurationmessage containing component carrier configuration information that iscommon to the plurality of UEs. For eNode B component carrierconfiguration information that is specific to the selected UE, the eNodeB can communicate (i.e. unicast) the specific component carrierinformation to the selected UE. For instance, dedicated communicationsignaling may be used. The module 808 is further configured to activateselected configured component carriers at the eNode B for the selectedUE based on at least one of quality of service needs and bandwidth ofthe selected UE.

It should be understood that many of the functional units described inthis specification have been labeled as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom VLSIcircuits or gate arrays, off-the-shelf semiconductors such as logicchips, transistors, or other discrete components. A module may also beimplemented in programmable hardware devices such as field programmablegate arrays, programmable array logic, programmable logic devices or thelike.

Modules may also be implemented in software for execution by varioustypes of processors. An identified module of executable code may, forinstance, comprise one or more physical or logical blocks of computerinstructions, which may, for instance, be organized as an object,procedure, or function. Nevertheless, the executables of an identifiedmodule need not be physically located together, but may comprisedisparate instructions stored in different locations which, when joinedlogically together, comprise the module and achieve the stated purposefor the module.

Indeed, a module of executable code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different storage devices, and may exist, atleast partially, merely as electronic signals on a system or network.The modules may be passive or active, including agents operable toperform desired functions.

Various techniques, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, CD-ROMs, hard drives, or any othermachine-readable storage medium wherein, when the program code is loadedinto and executed by a machine, such as a computer, the machine becomesan apparatus for practicing the various techniques. In the case ofprogram code execution on programmable computers, the computing devicemay include a processor, a storage medium readable by the processor(including volatile and non-volatile memory and/or storage elements), atleast one input device, and at least one output device. One or moreprograms that may implement or utilize the various techniques describedherein may use an application programming interface (API), reusablecontrols, and the like. Such programs may be implemented in a high levelprocedural or object oriented programming language to communicate with acomputer system. However, the program(s) may be implemented in assemblyor machine language, if desired. In any case, the language may be acompiled or interpreted language, and combined with hardwareimplementations.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as defactoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of materials, fasteners, sizes, lengths, widths, shapes, etc.,to provide a thorough understanding of embodiments of the invention. Oneskilled in the relevant art will recognize, however, that the inventioncan be practiced without one or more of the specific details, or withother methods, components, materials, etc. In other instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of the invention.

While the forgoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

1. A method for configuring component carriers in carrier aggregation,comprising: receiving a carrier aggregation capability from a selecteduser equipment (UE) at an enhanced Node B (eNode B) configured toprovide service for a plurality of UEs within the eNode B's network;configuring a plurality of component carriers at the eNode B for theselected UE based on the carrier aggregation capability of the selectedUE; broadcasting from the eNode B component carrier a configurationmessage containing component carrier configuration information that iscommon to the plurality of UEs; communicating from the eNode B componentcarrier configuration information that is specific to one of theplurality of UEs using dedicated communication signaling to formconfigured component carriers; and activating selected configuredcomponent carriers at the eNode B for the selected UE based on bandwidthand quality of service needs of the selected UE.
 2. The method of claim1, further comprising: receiving radio resource management (RRM)measurements of signal strength from each of the plurality of UEs at theeNode B for a plurality of component carriers available for carrieraggregation that are provided by the eNode B.
 3. The method of claim 2,wherein reporting RRM measurements of signal strength further comprisesmeasuring signal strength of each component carrier at each of theplurality of UEs using at least one of Reference Symbol Received Power(RSRP), Reference Symbol Received Quality (RSSQ), and Carrier ReceivedSignal Strength Indicator (RSSI) communicated via RRC signaling.
 4. Themethod of claim 2, wherein activating selected configured componentcarriers at the eNode B further comprises activating selected configuredcomponent carriers at the eNode B for the selected UE based on the RRMmeasurements provided by the selected UE following configuration.
 5. Themethod of claim 1, wherein receiving the carrier aggregation'scapability further comprises receiving at the eNode B from the selectedUE at least one of a maximum number of component carriers supported foran uplink to the eNode B, a maximum number of component carrierssupported for a downlink from the eNode B, a maximum bandwidth supportedfor the uplink and the downlink, and support of selected frequencybands.
 6. The method of claim 1, further comprising broadcastingcomponent carrier configuration information from the eNode B for eachcomponent carrier including: carrier center frequency, carrierbandwidth, and carrier duplex mode.
 7. The method of claim 1, furthercomprising assigning each component carrier at the eNode B: an eNode Bspecific carrier index (CI) provided in the broadcast configurationmessage; and a UE specific configured physical carrier index provided inthe dedicated communication signaling to reduce overhead whenreferencing each component carrier in communication between the eNode Band the plurality of UEs.
 8. The method of claim 1, further comprisingattaching the selected UE to one of the component carriers and definingthe component carrier as a primary component carrier (PCC).
 9. Themethod of claim 8, further comprising selecting a downlink of the PCC tocarry downlink control information (DCI) on a physical downlink controlchannel (PDCCH) for the plurality of component carriers.
 10. The methodof claim 1, further comprising selecting a downlink component carrier ofthe plurality of component carriers to carry downlink controlinformation (DCI) on a physical downlink control channel (PDCCH) for theplurality of component carriers.
 11. The method of claim 1, furthercomprising selecting an uplink component carrier for each downlinkcomponent carrier to carry physical uplink shared channel (PUSCH) anduplink feedback information on a physical uplink control channel(PUCCH), wherein the uplink component carrier is paired as part ofcarrier configuration with the downlink component carrier that is alsocarrying corresponding uplink assignments in the PDCCH.
 12. The methodof claim 8, further comprising selecting an uplink component carrier ofthe PCC to carry feedback information for each physical downlink sharedchannel (PDSCH) transmission on each downlink component carrier for theplurality of component carriers.
 13. The method of claim 1, furthercomprising carrying a physical hybrid ARQ (Automatic Repeat request)indicator channel (PHICH) on a same component carrier used to carry aphysical downlink control channel.
 14. The method of claim 1, whereincommunicating from the eNode B further comprises identifying in thecomponent carrier configuration information: for each downlink componentcarrier where a corresponding physical uplink control channel istransmitted; for each down link component carrier where a correspondingphysical downlink control channel is transmitted; for each uplinkcomponent carrier, where a corresponding physical downlink controlchannel is transmitted; and for a primary component carrier, whether arandom access channel is included.
 15. The method of claim 1, whereinactivating the selected configured component carriers further comprisestransmitting activation information as a media access control (MAC)control element from the eNode B to the selected UE for each componentcarrier.
 16. The method of claim 15, further comprising activating anddeactivating each component carrier for the selected UE using a bitmaptransmitted from the eNode B to the UE, wherein bits in the bitmap aremapped to an ordered list of indexes for the plurality of componentcarriers.
 17. The method of claim 16, further comprising transmittingone of a “1” and a “0” value at each bit in the bitmap to indicate oneof activation and deactivation of the component carrier.
 18. The methodof claim 1, further comprising deactivating selected component carriersbased on selected deactivation rules.
 19. A system for configuringcomponent carriers in carrier aggregation, comprising: a carrieraggregation module operating at an enhanced Node B (eNode B) configuredto provide service for a plurality of UEs, the carrier aggregationmodule configured to: receive a carrier aggregation capability at theeNode B from a carrier configuration module operating at a selected UE;configure a plurality of component carriers at the eNode B for theselected UE based on the carrier aggregation capability of the selectedUE; broadcast from the eNode B a component carrier configuration messagecontaining component carrier configuration information that is common tothe plurality of UEs; unicast from the eNode B to the selected UEcomponent carrier configuration information that is specific to theselected UE; and activate selected configured component carriers at theeNode B for the selected UE based on at least one of quality of serviceneeds and bandwidth needs of the selected UE.
 20. The system of claim19, wherein the carrier aggregation module at the eNode B is furtherconfigured to receive radio resource management (RRM) measurements ofsignal strength from each of the plurality of UEs for the plurality ofcomponent carriers available for carrier aggregation at the eNode B. 21.The system of claim 19, wherein the carrier aggregation module at theeNode B is further configured to communicate from the eNode B to theselected UE the component carrier configuration information that isspecific to the selected UE using level 2 communication.
 22. The systemof claim 19, wherein the carrier aggregation module at the eNode B isfurther comprised to communicate a component carrier bitmap to performat least one of activation and deactivation of selected componentcarriers for the selected UE using a bitmap transmitted from the eNode Bto the selected UE, wherein bits in the bitmap are mapped to an orderedlist of indexes for the plurality of component carriers.
 23. A computerprogram product, comprising a computer usable medium having a computerreadable program code embodied therein, the computer readable programcode adapted to be executed to implement a method for configuringcomponent carriers in carrier aggregation, comprising: receiving acarrier aggregation capability from a selected UE at an enhanced Node B(eNode B) configured to provide service for a plurality of UEs;configuring a plurality of component carriers at the eNode B for theselected UE based on the carrier aggregation capability of the selectedUE; broadcasting from the eNode B a component carrier configurationmessage containing component carrier configuration information that iscommon to the plurality of UEs; communicating from the eNode B componentcarrier configuration information that is specific to the selected UEusing dedicated communication signaling; receiving radio resourcemanagement (RRM) measurements of signal strength from each of theplurality of UEs at the eNode B; and activating selected configuredcomponent carriers from the eNode B for the selected UE based on thesignal strength measurements.
 24. The method of claim 23, whereinreceiving the carrier aggregation capability further comprises receivingat the eNode B from the selected UE at least one of a maximum number ofcomponent carriers supported for an uplink to the eNode B, a maximumnumber of component carriers supported for a downlink from the eNode B,a maximum bandwidth supported for the uplink and the downlink, andsupport of selected frequency bands.
 25. The method of claim 23, furthercomprising broadcasting from the eNode B component carrier configurationinformation for each component carrier, the component carrierconfiguration information including: a carrier center frequency of eachcomponent carrier, a carrier bandwidth of each component carrier, and acarrier duplex mode of an uplink and a downlink of each componentcarrier.
 26. The method of claim 23, further comprising activating anddeactivating each component carrier for the selected UE using a bitmaptransmitted from the eNode B to the UE, wherein bits in the bitmap aremapped to an ordered list of indexes for the plurality of componentcarriers.